Using DNA nanotechnology to build three-dimensional crystals

Using DNA nanotechnology to build three-dimensional crystals

In a major nanotech advance in constructing designer materials, DNA has been used to assemble gold nanoparticles into three-dimensional crystals.

Two research groups have made fundamental progress in using the molecular recognition properties of DNA strands to program the assembly of gold nanoparticles into three dimensional crystalline structures, in one case achieving two different crystalline structures according to the DNA sequences used. However the structures produced are not atomically precise, and the geometry of the nanoparticle networks is not directly programmable as it is with the “structural DNA nanotechnology” pioneered by Ned Seeman. Consequently it is unclear how useful these advances will be to the development of atomically precise manufacturing, despite the fact that they do indeed represent a “holy grail” in terms of using DNA nanotechnology to produce novel and useful nanomaterials.

In an achievement some see as the “holy grail” of nanoscience, researchers at the U.S. Department of Energy’s Brookhaven National Laboratory have for the first time used DNA to guide the creation of three-dimensional, ordered, crystalline structures of nanoparticles (particles with dimensions measured in billionths of a meter). The ability to engineer such 3-D structures is essential to producing functional materials that take advantage of the unique properties that may exist at the nanoscale — for example, enhanced magnetism, improved catalytic activity, or new optical properties.

Using just one kind of nanoparticle (gold) the researchers built two common but very different crystalline structures by merely changing one thing — the strands of synthesized DNA attached to the tiny gold spheres. A different DNA sequence in the strand resulted in the formation of a different crystal.

The technique … is a major and fundamental step toward building functional “designer” materials using programmable self-assembly. This “bottom-up” approach will allow scientists to take inorganic materials and build structures with specific properties for a given application, such as therapeutics, biodiagnostics, optics, electronics or catalysis.…

“We are now closer to the dream of learning, as nanoscientists, how to break everything down into fundamental building blocks, which for us are nanoparticles, and reassembling them into whatever structure we want that gives us the properties needed for certain applications,” said Chad A. Mirkin, one of the paper’s senior authors…

Both research reports were published in the same issue of Nature, and in a commentary in that issue John C. Crocker describes [subscription or payment required] the great potential of such engineered 3-D nanoparticle arrays, but also notes the limitations:

“The DNA in these experiments is being used in a fundamentally different way from its use in earlier DNA self-assembly techniques such as Ned Seeman’s ‘DNA tile’ approach. There, each constituent tile of the structure was made of interconnected DNA double strands. Each tile had one binding strand dangling from each corner, so that it could mate with neighbouring tiles. The structure of each tile was thus controlled at the molecular scale. The chemical process for attaching DNA strands to nanoparticles, by contrast, is essentially random, and scatters DNA strands over the gold sphere’s surface, rather than at just eight nearest-neighbour locations. The exact number of strands varies from sphere to sphere.”

This research has garnered quite a bit of attention, as seen by articles on:

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[…] Combining the novel electronic, magnetic, and optical properties of either semiconductor or metallic nanoparticles with the molecular recognition properties of DNA strands, nanotech has used DNA strands to assemble gold and other nanoparticles into distinct 1-dimensional or 2-dimensional structures, or into periodic 3-dimensional crystals (see this post from last year). Complementing these capabilities, structural DNA has provided complex structures from designed, branched DNA molecules, including DNA tiles that can be programmed to assemble into various two-dimensional arrays. Sometimes these arrays have been observed to curl into DNA nanotubes, probably due to difficult-to-predict steric effects. Now researchers have been able to attach gold nanoparticles to DNA tiles and, by varying the size of the nanoparticles and the presence of DNA stem loops on some tiles, have been able to control the formation from the DNA tiles of various three dimensional DNA nanotubes in which the gold nanoparticles form stacked rings, single spirals, double spirals, or nested spirals along the length of the DNA nanotube. From Arizona State University, via AAAS EurekAlert “The gold standard: Biodesign Institute researchers use nanoparticles to make 3-D DNA nanotubes“: […]